Introduction
You have learnt during lectures that there are multiple levels to the field of ecology, starting from the study of individual organisms (organismal ecology) through to populations, communities and ecosystems. There is also a branch known as landscape ecology and finally, global ecology.
There can sometimes be confusion among some ecological levels, particularly habitat, ecosystem and biomes. Typically, habitats are smaller components of an ecosystem (e.g. seagrass beds within a marine ecosystem) and you typically find many habitats within an ecosystem, but not the other way around. In contrast, biomes occur at a much broader scale and can consist or more than one ecosystem (e.g. tropical forest biomes can consist of both rainforest and dry forest ecosystems).
There are many kinds of ecosystems, ranging from wetlands, forests, grasslands, lakes and even urban housing estates, which all form types of ecosystems. It is important to note that the boundaries of different ecosystems are not always entirely clear, and specific ecosystems are often defined by individual researchers. However, all ecosystems include both living (biotic) and non-living (abiotic) components, which interact with each other. Even areas that are highly modified by human activity (e.g. football ovals and even urban areas) typically consist of these living and non-living components and their associated interactions.
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Two definitions of an ecosystem are:
All the organisms in a given area, along with the nonliving (abiotic) factors with which they interact: a biological community and its physical environment (Campbell et al. 2007).
An ecological community together with the physical environment with which its members interact (Knox et al. 2005)
Ecosystems are dynamic: that is, they change through time as the species in the community interact with each other and with the non-living components such as air, soil, water and rocks. As you will be aware, rainfall patterns change on a range of temporal scales, including daily, weekly and among seasons and years. This is just one example of changes in a single abiotic factor that could lead to a range of other changes in biotic components of the environment.
The aim of this exercise is to look closely at two areas within a single ecosystem (which may consist of two different habitats). For example, you may compare a patch of seagrass habitat with an algal bed or a pool habitat and riffle habitat within a single stream. A terrestrial example may include comparing the vegetation at the top of a slope with the vegetation at the base of a slope.
Alternatively, you could compare two separate ecosystems (e.g. a grassland versus a forest area). The purpose of the exercise is to help facilitate your understanding and appreciation of some key properties of an ecosystem. We will first consider the biotic components (living things) that make up an ecological community in an ecosystem, and their interrelationship with both other biotic components and also the abiotic components (i.e. non-living, inorganic components such as rocks, water and air amongst many other things). The exercise then asks you to think about (and consider) energy flow and chemical (nutrient) cycling in your chosen areas. Note that things that once were living, but are now dead (e.g. logs, dead leaves) are also regarded as biotic components (they are now non-living, but are derived from biotic components and are still largely organic).
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Further information that will assist you to understand ecosystems and successfully complete this assessment task can be found in your text (see pp 130-151). Information about ecosystems can also be found in most biology and ecology texts.
Methods
It is important to note that this task is not designed to teach you about appropriate experimental sampling designs (we want you to become more familiar with ecosystems at this stage). For example, if you are trying to determine differences between intertidal rocky shores and intertidal sandy shores, then it would be important to have replicate shores (i.e. sample at least 3 separate rocky shores and three separate sandy shores). However, this is beyond the scope of this particular exercise and you should be aware that any differences that you observe are limited to the two areas you have observed, which may or may not be related to differences in habitat (they could simply arise due to differences in space).
The first step of this exercise is to select an ecosystem (or ecosystems) to study. You should select places that are not only accessible, but also places that are of interest to you and where you enjoy visiting. Some examples might be:
– bush land
– park
– cemetery
– sand-dune
– an intertidal area
– a nearby stream, lake or wetland (including urban stormwater traps)
– a farm paddock
When you select your two study areas, try to ensure that they consist of a variety of different plants and try to choose relatively homogenous areas that are representative of the ecosystem. For example, avoid selecting areas that form the boundary between two areas/habitats (e.g. bush land and open grassland or the boundary between a seagrass bed and
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adjacent sandflat). You should also make sure that the size of your chosen area is large enough to sample five replicate 1m x 1m quadrats, and that it is of a similar overall size to the second area you choose to sample from. Make sure there is at least 100m separating your 2 chosen areas.
There are two important observations that we want you to make during this exercise:
Firstly, we want you to become familiar with the macroscopic primary producers in your 2 areas. This will involve two simple forms of ecological measurement including species counts (i.e. estimate plant species richness) and also the percent cover of plants.
Secondly, we want you to observe the diversity of macroscopic heterotrophs (animals and fungi). Macroscopic organism are those things that you can see with the naked eye.
You will need:
– notebook and pencils
– four pegs to mark the corners of a quadrat (e.g. tent pegs, short posts, sticks, long pencils
– a long ruler or tape measure (a dressmaker’s tape can be used too)
– a compass may be useful, to identify the position of your ecosystem (e.g. north- facing slope).
– you may need to take photographs of your plants for identification purposes (see video)
TO BEGIN:
Part 1. Recording species richness and percent cover of primary producers in your two areas.
1. Start by selecting a random point in your first area (you will repeat this for the second area). From this point, mark out a rectangular quadrat of 1 x 1 m with pegs. Please not that a quadrat is an area used for sampling and is usually square, rectangular or circular. It is not the same as a quadrant, which is a segment of a circle.
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2. Search carefully within the quadrat and count and record each different species of plant that you can find. You will not necessarily know the common names (or scientific names) of these plants, but you can give them descriptive names to recognise that they are different (e.g. Grass species A, Grass species B for two grasses that differ in their morphology such as leaf shape or seed heads). You can take photos of these as a reference for your remaining quadrats because you need to be consistent with your records as you move from one quadrat to the next. Enter the data from your first quadrat into Table 1 (see results section below).
3. Now estimate the percentage cover of your two most abundant primary producers in your quadrat. This will be explained to you during tutorials and we have provided a schematic diagram to assist you with this (Appendix 1). You should enter these data into Table 2 (see results section below).
4. Now repeat this procedure (counts of species richness and estimates of percentage cover) so that you have records for a total of 5 replicate 1m x 1m quadrats in your first chosen area.
5. Once you have completed your first 5 quadrats, move to your next area and repeat steps 1 – 4 so that you now have another set of 5 1m x 1m quadrats in area 2.
Here are some hints on how you could classify your terrestrial plants:
Grasses
usually green plants, often with blade-like leaves (from the Family Poaceae) (e.g. as seen in lawns, nature strips, grassland areas in parks)
Herbs
usually soft, green non-woody plants (i.e. other than grasses)
Shrubs
a ‘woody’ plant, usually with more than one main stem (usually < 3 m tall) Trees a tall woody plant, often > 5 m tall (and up to 30 m or more).
Climbers/twiners
non-woody plants that scramble along the ground or climb up other plants.
Your demonstrators can assist you with potential groupings of marine plants (e.g. green, red and brown algae) and seagrasses during seminars. Other marine habitats
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include saltmarshes, sand dunes
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Posted on May 16, 2016Author TutorCategories Question, Questions

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